This invention relates to certain substituted azetidinones having the structure 1: ##STR2## wherein R.sup.1, R.sup.2, R.sup.3 and R are defined below. Such azetidinones are useful in the preparation of certain substituted 1-carba-2-penem-3-carboxylic acids (I) and their pharmaceutically acceptable salt, ester and amide derivatives which are useful as antibiotics: ##STR3## Such 1-carba-2-penem-3-carboxylic acids are disclosed and claimed in co-pending, concurrently filed, commonly assigned, U.S. Patent Application Ser. No. 743,363, filed Nov. 19, 1976, now abandoned. Relative to 1 and I, R is hydrogen or an acyl or triorganosilyl blocking group and R.sup.1, R.sup.2 and R.sup.3 are independently selected from the group consisting of hydrogen substituted and unsubstituted: alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, alkylcycloalkyl, aryl, aralkyl, aralkenyl, aralkynyl, heteroaryl, heteroaralkyl, heterocyclyl and heterocyclylalkyl wherein the substituent or substituents relative to the above named radicals are selected from the group consisting of amino, hydroxy, alkoxyl, mercapto, alkylthio, arylthio, sulfamoyl, amidino, quanidino, nitro, chloro, bromo, fluoro, cyano and carboxy; and wherein the hetero atom in the above named heterocyclic moiety is selected from the group consisting of oxygen, nitrogen and sulphur.
This invention also relates to the pharmaceutically acceptable salt, ester and amide derivatives of the compounds of the present invention identified by structure (I), above.
This invention also relates to processes for the preparation of such compounds (I); pharmaceutical compositions comprising such compounds; and to methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.
There is a continuing need for new antibiotics. For unfortunately there is no static effectiveness of a given antibiotic because continued wide scale usage of any such antibiotic selectively gives rise to resistant strains of pathogens. In addition, the known antibiotics suffer from the disadvantage of being effective only against certain types of microorganisms. Accordingly the search for new antibiotics continues.
Thus, it is an object of the present invention to provide a novel class of antibiotics which are useful in animal and human therapy and in inanimate systems. These antibiotics are active against a broad range of pathogens which representatively include both gram positive bacteria such as S. aureus. Strep. pyogenes. Pseudomonas, and B. subtillis, and gram negative bacteria such as E. coli, Proteus morganii, Serratia and Klebsiella. Further objects of this invention are to provide chemical processes for the preparation of such antibiotics and their non-toxic pharmaceutically acceptable salts; pharmaceutical compositions comprising such antibiotics; and to provide methods of treatment comprising administering such antibiotics and compositions when an antibiotic effect is indicated.